The XtConvert function looks
up the type converter registered to convert from_type to to_type, computes
any additional arguments needed, and then calls XtDirectConvert. XtConvert
has been replaced by XtConvertAndStore.

The XtDirectConvert function
looks in the converter cache to see if this conversion procedure has been
called with the specified arguments. If so, it returns a descriptor for
information stored in the cache; otherwise, it calls the converter and
enters the result in the cache.

Before calling the specified converter,
XtDirectConvert sets the return value size to zero and the return value
address to NULL. To determine if the conversion was successful, the client
should check to_return.address for non-NULL. XtDirectConvert has been replaced
by XtCallConverter.